A number of thermal analysis methods have heretofore proven useful for probing the organic and mineral composition of insoluble hydrocarbon materials, such as coal, char, tar, lignins, wood, polymers, oil shale and petroleum source rock. Such techniques typically include subjecting the sample to dynamic pyrolysis conditions (normally, increasing the temperature at a constant rate), while monitoring weight loss and product evolution. For example, thermogravimetric analysis (TGA) has been carried out for the proximate analysis of coal, pyrolysis with detection of total hydrocarbons has been used for petroleum source rock evaluation, and pyrolysis with recovery of evolved products has been utilized for analysis of source rocks and sediments by gas chromatography. Non-optical thermal equipment, known as the Rockeval instrument used for total hydrocarbon analysis, is also commercially available.
A need exists, however, for a high-speed analytical instrument which more effectively provides information regarding composition, structure, and reaction mechanisms and kinetics for hydrocarbon materials, and particularly with respect to heavy, tarry constituents.
It is of course well known to utilize electromagnetic radiation for a variety of analytical purposes. A particularly effective tool of this nature is the Fourier-transform infrared (FT-IR) spectrometer, which utilizes wavenumber-dependent absorption data to permit the analysis of various properties of many different substances. Particularly unique and valuable applications for such apparatus are described and claimed in copending U.S. patent application Ser. No. 690,301, entitled "Method and Apparatus for Analyzing Particle-Containing Gaseous Suspensions" and filed on Jan. 10, 1985 in the names of Solomon, Carangelo and Best, which is of common assignment herewith. That application has now issued as U.S. Letters Patent No. 4,652,755, and the same subject matter was published on Jul. 17, 1986 as International Publication No. WO86/04140 under the Patent Cooperation Treaty. The description of the FT-IR spectrometer set forth therein, with reference to FIG. 1, is hereby incorporated into this disclosure by reference thereto.
Analytical apparatus have previously been proposed which couple the principles of TGA and FT-IR techniques. However, such instruments have not proven entirely satisfactory from a number of standpoints; this is particularly so in regard to the physical relationship between the TGA furnace and the FT-IR cell, and the structure through which the volatilized fractions of the sample must pass. Thus, in such earlier apparatus, difficulties have been encountered in ensuring that all products evolved are reliably introduced into the cell, and that the physical state or form thereof is optimal for the spectrometric analysis. Moreover, the information that is obtainable by use of such a technique and instrument has not heretofore been fully appreciated or utilized to maximum advantage.
Accordingly, it is an object of the present invention to provide a novel apparatus and method by which solid and liquid materials can be analyzed at a high rate of speed, to provide information concerning composition, structure, reaction mechanisms and kinetics, and the like.
It is a more specific object of the invention to provide such a method and apparatus wherein principles of thermogravimetric and Fourier-transform infrared analyses are combined in a highly effective and desirable manner, which apparatus may be self-calibrating.
It is also an object of the invention to provide such an apparatus in which products evolved by pyrolysis of the sample are introduced into an optical cell completely and in an optimal form for analysis.
A further more specific object of the invention is to provide such an apparatus and method, which are particularly well-suited for the analyses of typical insoluble hydrocarbons.
Additional objects of the invention are to provide a novel apparatus an method for performing proximate and ultimate analyses of coal, for performing analogous analyses of other substances, and for enabling determinations of calorific value, char reactivity, active site density, sulphur form identification, and other characterizing features of such materials.